Method for performing lithography process with post treatment

ABSTRACT

Methods for performing a lithography process are provided. The method for performing a lithography process includes forming a resist layer over a substrate and exposing a portion of the resist layer to form an exposed portion between unexposed portions. The method for performing a lithography process further includes developing the resist layer to remove the exposed portion of the resist layer such that an opening is formed between the unexposed portions and forming a post treatment coating material in the opening and over the unexposed portions of the resist layer. The method for performing a lithography process further includes reacting a portion of the unexposed portions of the resist layer with the post treatment coating material by performing a post treatment process and removing the post treatment coating material.

PRIORITY CLAIM AND CROSS-REFERENCE

This Application claims the benefit of U.S. Provisional Application No.62/549,607, filed on Aug. 24, 2017, and entitled “Lithography processwith post treatment and materials used thereof”, the entirety of whichis incorporated by reference herein.

BACKGROUND

Semiconductor devices are used in a variety of electronic applications,such as personal computers, cell phones, digital cameras, and otherelectronic equipment. Semiconductor devices are typically fabricated bysequentially depositing insulating or dielectric layers, conductivelayers, and semiconductor layers of material over a semiconductorsubstrate, and patterning the various material layers using lithographyto form circuit components and elements thereon.

One of the important drivers for increased performance in asemiconductor structure is the higher level of integration of circuits.This is accomplished by miniaturizing or shrinking device sizes on agiven chip. However, as the device sizes shrink, lithography processesused to form the devices also become more and more challenging.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It shouldbe noted that, in accordance with standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A to 1H show cross-sectional representations of various stages offorming a semiconductor structure including performing a lithographyprocess in accordance with some embodiments.

FIG. 2A illustrates a polymer in the post treatment coating materialthat has PAG/TAGs bonding to the polymer in accordance with someembodiments.

FIG. 2B illustrates a polymer and PAG/TAGs mixing in the post treatmentcoating material in accordance with some embodiments.

FIGS. 3A to 3C show cross-sectional representations of various stages ofperforming a lithography process in accordance with some embodiments.

FIGS. 4A to 4C show cross-sectional representations of various stages ofperforming a lithography process in accordance with some embodiments.

FIGS. 5A to 5C show cross-sectional representations of various stages ofperforming a lithography process in accordance with some embodiments.

FIGS. 6A and 6B illustrate the top views of unexposed portions of apatterned resist layer before and after the post treatment process isperformed in accordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the subject matterprovided. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

The advanced lithography process, method, and materials described in thecurrent disclosure can be used in many applications, including fin-typefield effect transistors (FinFETs). For example, the fins may bepatterned to produce a relatively close spacing between features, forwhich the above disclosure is well suited. In addition, spacers used informing fins of FinFETs can be processed according to the abovedisclosure.

Furthermore, spatially relative terms, such as “beneath,” “below,”“lower,” “above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. It should be understoodthat additional operations can be provided before, during, and after themethod, and some of the operations described can be replaced oreliminated for other embodiments of the method.

Embodiments of methods for performing a lithography process areprovided. The lithography process may include forming a resist layerover a substrate and performing an exposure process and a firstdeveloping process to the resist layer. Next, a post treatment coatingmaterial is formed over the resist layer and a post treatment process isperformed. Afterwards, the post treatment coating material is removed.By forming the post treatment coating material and performing the posttreatment process, the resolution of the resulting pattern in the resistlayer may be improved, and the energy required to be consumed for thelithography process may be reduced.

FIGS. 1A to 1H show cross-sectional representations of various stages offorming a semiconductor structure 100 including performing a lithographyprocess in accordance with some embodiments. As shown in FIG. 1A, asubstrate 102 is received in accordance with some embodiments. Thesubstrate 102 may be a semiconductor wafer such as a silicon wafer.Alternatively or additionally, the substrate 102 may include elementarysemiconductor materials, compound semiconductor materials, and/or alloysemiconductor materials. Examples of the elementary semiconductormaterials may include, but are not limited to, crystal silicon,polycrystalline silicon, amorphous silicon, germanium, and diamond.Examples of the compound semiconductor materials may include, but arenot limited to, silicon carbide, gallium arsenic, gallium phosphide,indium phosphide, indium arsenide, and indium antimonide. Examples ofthe alloy semiconductor materials may include, but are not limited to,SiGe, GaAsP, AlInAs, AlGaAs, GaInAs, GaInP, and GaInAsP.

In some embodiments, the substrate 102 includes structures such as dopedregions including wells and source/drain regions, isolation featuresincluding shallow trench isolation (STI), inter-level dielectric (ILD)layers, and/or conductive features including gate electrodes, metallines, vias, and contacts.

A material layer 104 is formed over the substrate 102, as shown in FIG.1A in accordance with some embodiments. The material layer 104 isconfigured to be patterned in subsequent manufacturing processes. Thematerial layer 104 may be one or more material layers. In someembodiments, the material layer 104 is a dielectric layer. In someembodiments, the material layer 104 is made of metal oxides, metalnitrides, metal silicates, transition metal-oxides, transitionmetal-nitrides, transition metal-silicates, or oxynitrides of metals.Examples of materials used to form the material layer 104 include, butare not limited to, titanium oxide, titanium nitride, hafnium oxide(HfO₂), hafnium silicon oxide (HfSiO), hafnium silicon oxynitride(HfSiON), hafnium tantalum oxide (HfTaO), hafnium titanium oxide(HfTiO), hafnium zirconium oxide (HfZrO), silicon nitride, siliconoxynitride, zirconium oxide, titanium oxide, aluminum oxide, hafniumdioxide-alumina (HfO₂—Al₂O₃) alloy, or other applicable dielectricmaterials. In some embodiments, the material layer 104 is made of low-kdielectric materials. In some embodiments, the material layer 104 ismade of silicon oxide, silicon nitride, silicon oxynitride,phosphosilicate glass (PSG), borophosphosilicate glass (BPSG), and/orother applicable low-k dielectric materials. In some embodiments, thematerial layer 104 is formed by performing a chemical vapor deposition(CVD) process, a physical vapor deposition (PVD) process, an atomiclayer deposition (ALD) process, a spin-on coating process, or otherapplicable processes.

After the material layer 104 is formed, a resist layer 106 is formedover the material layer 104, as shown in FIG. 1A in accordance with someembodiments. In some embodiments, the resist layer 106 is formed bycoating a resist material over the material layer 104. In someembodiments, the resist material used to form the resist layer 106includes photosensitive polymers, photo-acid generators (PAG),quenchers, and a solvent. The photosensitive polymers may releaseelectrons as being exposed to a radiation, and the electrons may inducethe PAG to release acids to form an acidic environment. Next, acidlabile functional groups at the photosensitive polymers may then bereleased in the acidic environment, and the acid labile functional groupof the photosensitive polymer may be transformed into acid groups (e.g.deprotected). Accordingly, the photosensitive polymers may be insolublein a developer used in a developing process before performing anexposure process but become soluble in the developer after performing anexposure process.

After the resist layer 106 is formed, an exposure process 108 isperformed on the resist layer 106 to form a patterned resist layer 106′,as shown in FIG. 1B in accordance with some embodiments. Morespecifically, a mask structure 110 having an opening 112 is positionedover the resist layer 106 during the exposure process 108 to form anexposed portion 114 and unexposed portions 116. In some embodiments, theexposed portion 114 is located between the unexposed portions 116.

In some embodiments, the exposure process 108 includes exposing theexposed portion 114 to a radiation. In some embodiment, the radiationhas a wavelength smaller than 250 nm. In some embodiments, the radiationincludes KrF, ArF, EUV, or E-beam. More specifically, the photosensitivepolymers in the exposed portion 114 of the patterned resist layer 106′will release electrons as being exposed to the radiation during theexposure process, and the electrons will induce the PAG to releaseacids, resulting in an acidic environment. Accordingly, acid labilefunctional groups at the photosensitive polymers will be released in theacidic environment, and therefore the photosensitive polymers willbecome soluble in the developer used afterwards. After the exposureprocess 108 is performed, the mask structure 110 is removed.

In some embodiments, the patterned resist layer 106′ is baked (e.g.heated) after the exposure process 108 is performed. In someembodiments, the amount of acid groups (e.g. —COOH group) in the exposedportion 114 of the patterned resist layer 106′ increases after thepatterned resist layer 106′ is baked, so that the exposed portion 114become more soluble than before it is baked.

Next, a first developing process is performed on the patterned resistlayer 106′ to remove the exposed portions 114, such that an opening 118is formed between the unexposed portions 116, as shown in FIG. 1C inaccordance with some embodiments. More specifically, the exposedportions 116 of the patterned resist layer 106″ are dissolved in a firstdeveloper used in the first developing process and are removed with thefirst developer. As described previously, the acid groups of the exposedportion 114 of the patterned resist layer 106′ are de-protected in theacidic environment and therefore the exposed portion 114 become solublein the first developer used in the first developing process. On theother hand, the unexposed portions 116 are not exposed to a radiationduring the exposure process 108, and the unexposed portions 116 of thepatterned resist layer 106′ remains insoluble in the first developerduring the first developing process. In some embodiments, the firstdeveloper includes tetramethylammonium hydroxide (TMAH).

After the first developing process is performed, a post treatmentcoating material 120 is formed in the opening 118 and over the unexposedportions 116, as shown in FIG. 1D in accordance with some embodiments.In addition, the opening 118 is fully filled with the post treatmentcoating material 120 in accordance with some embodiments. The posttreatment coating material 120 may be a precursor for releasing acids,so that the acids produced by the post treatment coating material 120may react with the peripheral portion of the unexposed portions 116. Insome embodiments, the post treatment coating material 120 includesphoto-acid generator (PAG) and thermal acid generator (TAG). Details ofthe post treatment coating material 120 will be described afterwards.

After the post treatment coating material 120 is formed, a posttreatment process 122 is performed onto the post treatment coatingmaterial 120, as shown in FIG. 1E in accordance with some embodiments.The post treatment process 122 is configured to induce the formation ofacids in the post treatment coating material 120, so that the acids mayreact with the peripheral portion 124 of the unexposed portions 116. Insome embodiments, the acids released during the post treatment process122 has a pKa value less than about 3. In addition, the post treatmentprocess 122 may be configured to control the diffusion distance of thepost treatment coating material 120, so that the size of the resultingunexposed portions may be formed as designed (Details will be describedlater.)

In some embodiments, the post treatment process 122 is a thermal bakingprocess. As described above, the post treatment coating material 120 mayinclude thermal acid generators which tend to release acids when thepost treatment coating material 120 is heated. Accordingly, the posttreatment process 122 may be a thermal baking process, so that thethermal acid generators may be decomposed during the post treatmentprocess 122 to release acids in the post treatment coating material 120.

In some embodiments, the post treatment process 122 includes heating thepost treatment coating material 120 under a temperature in a range ofabout 60° C. to about 200° C. In some embodiments, the post treatmentcoating material 120 is heated for about 5 sec to about 300 sec. Thetemperature and the time for performing the post treatment process 122is controlled to be high/long enough to trigger the reaction between thepost treatment coating material 120 and the unexposed portion 116. Onthe other hand, the temperature and the time for performing the posttreatment process 122 should not be too high/long, orintermixing/diffusion between the post treatment coating material 120and the unexposed portions may become too much.

In some embodiments, the post treatment process 122 is a radiationcuring process. In some embodiments, the radiation curing processincludes exposing the post treatment coating material 120 to aradiation. In some embodiment, the radiation has a wavelength smallerthan 365 nm. In some embodiments, the radiation includes i-line, KrF,ArF, EUV, or E-beam.

As described above, the post treatment coating material 120 may includephoto-acid generators which tend to release acids when the posttreatment coating material 120 reacts with radiation. Accordingly, thepost treatment process 122 may be a radiation curing process, so thatthe photo-acid generators may be decomposed during the post treatmentprocess 122 to release acids in the post treatment coating material 120.

In some embodiments, the post treatment coating material 120 may diffusefrom the top surface and the sidewalls of the unexposed portions 116toward the center of the unexposed portions 116, and the post treatmentcoating material 120 will release acids, so that the acids will reactwith the unexposed portions 116 of the patterned resist layer 106 duringthe post treatment process 122. For example, the acids may react withthe peripheral portion 124 of the unexposed portion 116 of the patternedresist layer 106″.

In some embodiments, the peripheral portion 124 of the unexposed portion116 of the patterned resist layer 106″ has a thickness in a range fromabout 1 nm to about 50 nm. The peripheral portion 124 of the unexposedportion 116 of the patterned resist layer 106″ may be defined as theportion of the unexposed portion 116 reacting with the acids releasedfrom the post treatment coating material 120.

After the post treatment process 122 is performed, a second developingprocess is performed to remove the post treatment coating material 120,as shown in FIG. 1F in accordance with some embodiments. In addition,the peripheral portions 124 of the unexposed portions 116 are alsoremoved by the second developing process in accordance with someembodiments.

More specifically, a second developer is used in the second developingprocess, and both the post treatment coating material and the peripheralportions 124 of the unexposed portions 116 are dissolved in the seconddeveloper in accordance with some embodiments. In some embodiments, thesecond developer used in the second developing process is the same asthe first developer used in the first developing process describedabove. In some embodiments, the second developer includestetramethylammonium hydroxide (TMAH). In some embodiments, the seconddeveloper includes 2.38% of TMAH or less than 2.38% of TMAH solution.

Since the peripheral portions 124 of the unexposed portions 116 areremoved by the second developing process, the size of the unexposedportion 116′ of the patterned resist layer 106″′ shown in FIG. 1F issmaller than the size of the unexposed portion 116 of the patternedresist layer 106″ shown in FIG. 1E in accordance with some embodiments.That is, the distance D₂ between the unexposed portions 116′ shown inFIG. 1F is greater than the distance D₁ between the unexposed portion116 shown in FIG. 1E.

In some embodiments, the width W₁ of the unexposed portion 116 of thepatterned resist layer 106″ shown in FIG. 1E is greater than the widthW₂ of the unexposed portion 116′ of the patterned resist layer 106″′shown in FIG. 1F. In some embodiments, the difference between the widthW₁ and the width W₂ is in a range from about 1 nm to about 50 nm. Sincethe width W₁ of the unexposed portion 116 can be reduced by performingthe post treatment process, the energy used in the exposure process 108may be reduced (Details will be described later.)

In some embodiments, the height H₁ of the unexposed portion 116 of thepatterned resist layer 106″ shown in FIG. 1E is greater than the heightH₂ of the unexposed portion 116′ of the patterned resist layer 106″′shown in FIG. 1F. In some embodiments, the difference between the heightH₁ and the height H₂ is in a range from about 1 nm to about 50 nm. Sincethe height H₂ of the unexposed portion 116 can be reduced by performingthe post treatment process, the aspect ratio of the unexposed portion116 may also be reduced. Therefore, risks of bending or cracking of theresist layer due to the high aspect ratio (or large height) may also bereduced.

Next, an etching process 130 is performed to etch the material layer 104using the unexposed portions 116′ as masks, as shown in FIG. 1G inaccordance with some embodiments. In some embodiments, the etchingprocess 130 is a dry etching process, such as a plasma etching process.After the etching process 130 is performed, the material layer 104 ispatterned to form patterns 126 of the patterned material layer 104′. Inaddition, an opening 128 is formed between the patterns 126 of thepatterned material layer 104′, as shown in FIG. 1G in accordance withsome embodiments.

After the etching process 130 is performed, the unexposed portions 116′of the patterned resist layer 106′″ are removed, as shown in FIG. 1H inaccordance with some embodiments. The patterns 126 may have a widthsubstantially equal to the width W₂ of the unexposed portion 116′ shownin FIG. 1E. In addition, the distance between the patterns 126 in thepatterned material layer 104′ may be substantially equal to the distanceD2 between the unexposed portions 116′ shown in FIG. 1E.

As described previously, the method for manufacturing the semiconductorstructure 100 includes performing a lithography process using the posttreatment coating material 120 and performing the post treatment process122 in accordance with some embodiments. More specifically, the posttreatment coating material 120 is formed over the patterned resist layer106′ and the post treatment process 122 is performed afterwards. Inaddition, the post treatment coating material 120 is configured to be aprecursor for releasing acids, so that the acids produced by the posttreatment coating material 120 may react with the peripheral portions124 of the unexposed portions 116.

In some embodiments, the post treatment coating material 120 includes apolymer, a photo-acid generator (PAG) and/or a thermal acid generator(TAG), and a solvent. The solvent may be chosen so that it will notintermix with the resist layer 106. That is, the resist layer 106 shouldbe insoluble to the solvent of the post treatment coating material 120.In some embodiments, the solvent is alcohol, ether, ester, or the like.In some embodiments, the solvent is H₂O, methanol, ethanol, propanol,butanol, isopropyl alcohol (IPA), ethylene glycol, methyl isobutylcarbinol (MIBC), diisopentyl ether (DIAE), dimethyl ether, diethylether, dipropyl ether, dibutyl ether, normal butyl acetate (NBA), orcombinations thereof.

The polymer in the post treatment coating material 120 may include PAGand/or TAGs bonding thereto or may be blended with PAG and/or TAGs. FIG.2A illustrates a polymer 20A in the post treatment coating material 120that has PAG/TAGs bonding to the polymer in accordance with someembodiments.

As shown in FIG. 2A, the polymer 20A has a main chain and at least twofunctional groups bonding to the main chain. The first functional groupA is configured to adjust the solubility of the polymer 20A and thesecond functional group is configured to release acids in the posttreatment coating material 120.

In particular, the polymer is designed to be soluble in the solvent butthe resist layer 106 should be in-soluble to the solvent. In someembodiments, the first functional group A is a moiety of a monomer Awith acidity. In some embodiments, the pKa value of the monomer A isless than 4.5. In some embodiments, the first functional group A is amoiety of mathacrylic acid (MAA), methyl methacrylate (MMA), vinylalcohol, hydroxystyrene (HS), 4-styrenesulfonic acid, fluoro-alcoholsubstituted alkane, or a fluorine substituted alkane. In someembodiments, the first functional group A is a fluoro-alcoholsubstituted alkyl group or a fluorine substituted alkyl group. In someembodiments, the first functional group A is a fluorine-substitutedC₁-C₁₀ alkyl group.

In some embodiments, the second functional group is a moiety of PAG orTAG. For example, the PAG/TAG may be bonded to the main chain of thepolymer 20A through a covalent bond. In some embodiments, the secondfunctional group is a moiety of the following formula (I):

In some embodiments, R in formula (I) is C₁-C₁₀ alkyl, C₃-C₁₀ alkenyl,C₃-C₁₀ alkynyl, or C₁-C₁₀ alkoxy, and R₁ in formula (I) is hydrogen,C₁-C₁₀ alkyl, C₃-C₁₀ alkenyl, C₃-C₁₀ alkynyl, or C₁-C₁₀ alkoxy. In someembodiments, R in formula (I) is a fluorine-substituted alkyl group,such as a fluorine-substituted C₁-C₁₀ alkyl group. In some embodiments,the molecular weight of R in formula (I) is greater than 15. In someembodiments, the molecular weight of R in formula (I) is in a range fromabout 15 to about 500. The molecular weight of the R group should begreat enough to limit the diffusion of the polymer. In some embodiments,a carbon in the R group of the compound shown in formula (I) is bondedto the main chain of the polymer 20A through a covalent bond.

In some embodiments, the second functional group is a moiety of thefollowing formula (II):

In some embodiments, R in formula (II) is C₁-C₁₀ alkyl, C₃-C₁₀ alkenyl,C₃-C₁₀ alkynyl, or C₁-C₁₀ alkoxy. In some embodiments, R in formula (II)is a fluorine-substituted alkyl group, such as a fluorine-substitutedC₁-C₁₀ alkyl group. In some embodiments, the molecular weight of R informula (II) is greater than 15. In some embodiments, the molecularweight of R in formula (II) is in a range from about 15 to about 500.The molecular weight of the R group should be great enough to limit thediffusion distance of the polymer. In some embodiments, a carbon in theR group of the compound shown in formula (II) is bonded to the mainchain of the polymer 20A through a covalent bond.

In some embodiments, the second functional group is a moiety of thefollowing formula (III):

In some embodiments, R in formula (III) is C₁-C₁₀ alkyl, C₃-C₁₀ alkenyl,C₃-C₁₀ alkynyl, or C₁-C₁₀ alkoxy. In some embodiments, R in formula(III) is a fluorine-substituted alkyl group, such as afluorine-substituted C₁-C₁₀ alkyl group. R₁ in formula (III) ishydrogen, C₁-C₁₀ alkyl, C₃-C₁₀ alkenyl, C₃-C₁₀ alkynyl, or C₁-C₁₀alkoxy. In some embodiments, the molecular weight of R in formula (III)is greater than 15. In some embodiments, the molecular weight of R informula (III) is in a range from about 15 to about 500. The molecularweight of the R group should be great enough to limit the diffusion ofthe polymer. In some embodiments, a carbon in the R group of thecompound shown in formula (III) is bonded to the main chain of thepolymer 20A through a covalent bond.

In some embodiments, the polymer 20A has a weight average molecularweight in a range from about 2000 to about 500000. As described above,the size (i.e. molecular weight) of the polymer 20A may be controlled sothat the diffusion distance of post treatment coating material 120 maybe easier to control.

In some embodiments, the mole ratio of the first functional group to thesecond functional group is in a range from about 1 to about 100. Asdescribed above, the first functional group may be seen as a solubilitycontroller, and the second functional group may be seen as an acidgenerator. More specifically, the first functional group A is configuredto adjust the solubility of the polymer 20A and the second functionalgroup is configured to release acids in the post treatment coatingmaterial 120. Therefore, the ratio of the first functional group to thesecond functional group may be controlled so that a proper amount of theacids can be released from the polymer 20A and the polymer 20A can besoluble in the solvent in the post treatment coating material.

In some other embodiments, the polymer in the post treatment coatingmaterial 120 is blended with PAG and/or TAG. FIG. 2B illustrates apolymer 20B and PAG/TAGs mixing in the post treatment coating material120 in accordance with some embodiments. As shown in FIG. 2B, thepolymer 20B has a main chain and the first functional group A bonding tothe main chain. The first functional group A is configured to adjust thesolubility of the polymer 20A. Examples of the first functional group Ashown in FIG. 2B may be similar to, or the same as, those of the firstfunctional group A shown in FIG. 2A and described above and are notrepeated herein.

As shown in FIG. 2B, PAG/TAG is not chemically bonded to the polymer 20Bbut is mixed with the polymer 20B in accordance with some embodiments.In some embodiments, the PAG/TAG has the following formula (I), (II), or(III):

In some embodiments, R in formula (I), (II), and (III) are independentlyselected from C₁-C₁₀ alkyl, C₃-C₁₀ alkenyl, C₃-C₁₀ alkynyl, and C₁-C₁₀alkoxy. In some embodiments, R in formula (II) is a fluorine-substitutedalkyl group, such as a fluorine-substituted C₁-C₁₀ alkyl group. R₁ informula (I) and (III) are independently selected from hydrogen, C₁-C₁₀alkyl, C₃-C₁₀ alkenyl, C₃-C₁₀ alkynyl, and C₁-C₁₀ alkoxy. In someembodiments, the molecular weight of R in formula (I), (II), and (III)is greater than 15. In some embodiments, the molecular weight of R informula (I), (II), and (III) is in a range from about 15 to about 500.In some embodiments, the PAG has a molecular weight in a range fromabout 300 to about 1000. In some embodiments, the TAG has a molecularweight in a range from about 60 to about 600. Similar to the PAG/TAGshown in FIG. 2A and described above, the PAG/TAG in the mixture of thepolymer 20B and PAG/TAG is configured to release acids in the posttreatment coating material 120.

In some embodiments, the amount of TAG/PAG is greater than 0.1 wt %. Insome embodiments, the amount of TAG/PAG is in a range from about 1 wt %to about 30 wt %. In some embodiments, the amount of TAG/PAG is in arange from about 1 wt % to about 70 wt %.

As described above, the post treatment coating material 120 covers thetop surfaces and the sidewalls of the unexposed portions 116 (e.g. FIG.1D). After the post treatment coating material 120 is formed, the posttreatment process 122 is performed (e.g. FIG. 1E) to produced acids inthe post treatment coating material 120.

In some embodiments, the post treatment coating material 120 includesPAG, and therefore a radiation curing process is performed as the posttreatment process 122, so that acids are formed in the post treatmentcoating material 120 in accordance with some embodiments. In some otherembodiments, the post treatment coating material 120 includes TAG, andtherefore a thermal baking process is performed as the post treatmentprocess 122, so that acids are formed in the post treatment coatingmaterial 120.

As described previously, the resist layer 106 may be made ofphotosensitive polymers and the photosensitive polymers may include acidlabile functional groups. Therefore, when the acids are formed in thepost treatment coating material 120 during the post treatment process122, the acids will react with the unexposed portions 116 of thepatterned resist layer 106″, such that the acid labile functional groupsin the unexposed portions 116 of the patterned resist layer 106″ will bereleased in the acidic environment and will be transformed into acidgroups (e.g. —COOH). That is, the portions of the unexposed portions 116of the patterned resist layer 106″ reacting with the acids released bythe post treatment coating material 120 may become soluble in adeveloper (e.g. the second developer) while the portions of theunexposed portions 116 not react with the acids remain insoluble to thedeveloper.

In some embodiments, the post treatment coating material 120 diffusesinto the peripheral portions 124 of the unexposed portions 116, so thatthe peripheral portions 124 of the unexposed portions 116 can react withthe acids released in the post treatment material 120 and be dissolvedin the second developer. Therefore, the peripheral portions 124 of theunexposed portions 116 can be removed during the second developingprocess.

Accordingly, the distance D₂ between the unexposed portions 116′ shownin FIG. 1F is greater than the distance D₁ between the unexposedportions 116 that is formed by the exposure process 108 and the firstdeveloping process shown in FIG. 1C. Therefore, although the finalopening 128 between the patterns 126 of the patterned material layer104′ has the distance D₂, the energy (e.g. radiation) used in themanufacturing process only need to expose the exposed portion 114 shownin FIG. 1B that has the distance D₁, which is shorter than D₂. That is,the energy required to form the patterns 126 may be reduced.

It should be noted that although the unexposed portions 116′ of thepatterned resist layer 106′″ are used as masks in the etching process124 for patterning the material layer 104, the unexposed portions 116′of the patterned resist layer 106′″ may be used for different purposesin other embodiments. For example, the unexposed portions 116′ of thepatterned resist layer 106′″ may be used as masks in an implantationprocess to implant dopants in the portions of material layer not coveredby the unexposed portions 116′.

FIGS. 3A to 3C show cross-sectional representations of various stages ofperforming a lithography process in accordance with some embodiments.The lithography process shown in FIGS. 3A to 3C may be similar to thelithography process shown in FIGS. 1A to 1H, except some portions of theexposed portions of the resist layer remain on the material layer 104after the first developing process is performed. Some materials andprocesses of the lithography process shown in FIGS. 3A to 3C may besimilar to, or the same as, those shown in FIGS. 1A to 1H and are notrepeated herein.

In particular, an exposure process similar to those shown in FIGS. 1Aand 1B may be performed, and a first developing process may be performedto remove the exposed portions of the patterned resist layer 106 a″, asshown in FIG. 3A in accordance with some embodiments. However, unlikethose shown in FIG. 1C, the exposed portions of the patterned resistlayer 106 a″ are only partially removed by the first developing process.As shown in FIG. 3A, remaining portions 306 of the exposed portions ofthe patterned resist layer 106 a″ remain at the bottom portion of thesidewalls of the unexposed portions 116 a in accordance with someembodiments. In some embodiments, the remaining portions 306 of theexposed portions of the patterned resist layer 106 a″ also cover aportion of the material layer 104 over the substrate 102.

After the first developing process is performed to at least partiallyremove the exposed portions, a post treatment coating material 120 a isformed to cover the patterned resist layer 106 a″, as shown in FIG. 3Bin accordance with some embodiments. In some embodiments, the posttreatment coating material 120 a is directly formed on the top surfaceand the sidewalls of the unexposed portions 116 a and on the remainingportions 306 of the exposed portions of the patterned resist layer 106a″. The materials for forming the post treatment coating material 120 amay be similar to, or the same as, the materials for forming the posttreatment coating material 120 described previously and are not repeatedherein.

After the post treatment coating material 120 a is formed, a posttreatment process is performed first and a second developing process isperformed afterwards to remove the post treatment coating material 120a, as shown in FIG. 3C in accordance with some embodiments. In addition,the remaining portions 306 of the exposed portions are also removed inthe second developing process. The post treatment process and the seconddeveloping process may be similar to, or the same as, the post treatmentprocess 122 and the second developing process shown in FIGS. 1A to 1Hdescribed previously.

More specifically, the post treatment coating material 120 releasesacids during the post treatment process, so that the remaining portions306 of the exposed portions of the patterned resist layer 106 a″ reactwith the acids and become soluble in the second developer used in thesecond developing process in accordance with some embodiments. Inaddition, the periphery portion of the unexposed portions 116 a may alsoreact with the acids and become soluble in the second developer used inthe second developing process. That is, both the remaining portions 306of the exposed portions and the periphery portion of the unexposedportions 116 a are dissolved in the second developer in the seconddeveloping process in accordance with some embodiments.

Accordingly, the size of the resulting unexposed portions 116 a′ of thepatterned resist layer 106 a″′ shown in FIG. 3C is smaller than the sizeof the unexposed portion 116 a shown in FIG. 3A in accordance with someembodiments. The differences of their heights and widths between theunexposed portions 116 a′ and the unexposed portion 116 a may be similarto, or the same as, those between the unexposed portions 116′ shown inFIG. 1F and the unexposed portion 116 shown in FIG. 1E describedpreviously and are not repeated herein.

As described previously, the patterned resist layer 106 a″′ may be usedas masks for patterning the material layer 104 therebelow. Therefore, ifthe remaining portions 306 of the exposed portions are not removed, theresolution of the resulting pattern of the material layer 104 may bereduced. Accordingly, by applying the post treatment coating material120 a and the post treatment process, the resolution of the lithographyprocess may be improved.

FIGS. 4A to 4C show cross-sectional representations of various stages ofperforming a lithography process in accordance with some embodiments.The lithography process shown in FIGS. 4A to 4C may be similar to thelithography process shown in FIGS. 3A to 3C, except the remainingportions of the exposed portions of patterned the resist layer islocated at the upper portion of the unexposed portions. Some materialsand processes of the lithography process shown in FIGS. 4A to 4C may besimilar to, or the same as, those shown in FIGS. 1A to 1H and 3A to 3Cand are not repeated herein.

In particular, an exposure process similar to those shown in FIGS. 1Aand 1B may be performed, and a first developing process may be performedto partially remove the exposed portions of the patterned resist layer106 a″, such that remaining portions 406 of the exposed portions of thepatterned resist layer 106 b″ remain at the upper portion of thesidewalls of the unexposed portions 116 b, as shown in FIG. 4A inaccordance with some embodiments.

Afterwards, a post treatment coating material 120 b is formed to coverthe patterned resist layer 106 b″, as shown in FIG. 4B in accordancewith some embodiments. The materials for forming the post treatmentcoating material 120 b may be similar to, or the same as, the materialsfor forming the post treatment coating material 120 described previouslyand are not repeated herein.

After the post treatment coating material 120 b is formed, a posttreatment process is performed first and a second developing process isperformed afterwards to remove the post treatment coating material 120b, as shown in FIG. 4C in accordance with some embodiments. In addition,both the remaining portions 406 of the exposed portions and theperiphery portion of the unexposed portions 116 b are dissolved in thesecond developer in the second developing process in accordance withsome embodiments. The resulting unexposed portion 116 b of the patternedresist layer 106 b″′ shown in FIG. 4C may be similar to, or the same as,the unexposed portion 116 a shown in FIG. 3C and therefore details ofits structure are not repeated herein.

In some other embodiments, the remaining portions 406 of the exposedportions may form bridges between the unexposed portions, and thesebridges may also be removed by applying the post treatment coatingmaterial 120 b and the post treatment process. Accordingly, theresolution of the lithography process may be improved.

FIGS. 5A to 5C show cross-sectional representations of various stages ofperforming a lithography process in accordance with some embodiments.The lithography process shown in FIGS. 5A to 5C may be similar to thelithography process shown in FIGS. 1A to 1F, except a polymer layer isformed over the material layer after the first developing process isperformed. Some materials and processes of the lithography process shownin FIGS. 5A to 5C may be similar to, or the same as, those shown inFIGS. 1A to 1H and are not repeated herein.

In particular, an exposure process similar to those shown in FIGS. 1Aand 1B is performed, and a first developing process is performed toremove the exposed portions of the patterned resist layer 106 c″, asshown in FIG. 5A in accordance with some embodiments. In addition, apolymer layer 506 is formed over the top surface of the material layer104 during the first developing process in accordance with someembodiments. The formation of the polymer layer 506 may result from theinterfacial adhesion between the material layer 104 andparticles/compounds over the material layer 104 during the firstdeveloping process. In some embodiments, the polymer layer 506 includesthe residues of the exposed portion of the patterned resist layer 106 c″and the first developer used in the first developing process.

Afterwards, a post treatment coating material 120 c is formed to coverthe patterned resist layer 106 c″, as shown in FIG. 5B in accordancewith some embodiments. In some embodiments, the post treatment coatingmaterial 120 c is directly formed on the top surface and the sidewallsof the unexposed portions 116 c and on the polymer layer 506. Thematerials for forming the post treatment coating material 120 c may besimilar to, or the same as, the materials for forming the post treatmentcoating material 120 described previously and are not repeated herein.

After the post treatment coating material 120 c is formed, a posttreatment process is performed first and a second developing process isperformed afterwards to remove the post treatment coating material 120 cand the polymer layer 506, as shown in FIG. 5C in accordance with someembodiments. In some embodiments, the polymer layer 506 and the topportion of the unexposed portions 116 c are both dissolved in the seconddeveloper in the second developing process. The resulting unexposedportion 116 c of the patterned resist layer 106 c″′ shown in FIG. 5C maybe similar to, or the same as, the unexposed portion 116 shown in FIG.1F and therefore details of its structure are not repeated herein.

As described previously, the size of the unexposed portions of thepatterned resist layers (e.g. the unexposed portions 116, 116 a, 116 b,and 116 c) before the post treatment process is performed is greaterthan the size of the unexposed portions of the patterned resist layers(e.g. the unexposed portions 116′, 116 a′, 116 b′, and 116 c′) after thepost treatment process is performed. In addition, the line/space profileof the patterned resist layer may be trimmed to have improved line widthroughness/line edge roughness. FIGS. 6A and 6B illustrate the top viewsof unexposed portions of a patterned resist layer before and after thepost treatment process is performed in accordance with some embodiments.

More specifically, FIG. 6A illustrates the top view of the unexposedportions 116 d of the patterned resist layers before the post treatmentprocess is performed, and FIG. 6B illustrates the top view of theunexposed portions 116 d′ of the patterned resist layers after the posttreatment process is performed in accordance with some embodiments. Whenunexposed portion 116 d reacts with acids during the post treatmentprocess (e.g. the post treatment process 122), the polymer of theunexposed portion 116 d may be redistributed and therefore the profileof the unexposed portion 116 d may be smoothened. Accordingly, theresulting unexposed portions 116 d′ may have an improved line widthroughness/line edge roughness.

The unexposed portions 116 d shown in FIG. 6A may be similar to theunexposed portions 116, 116 a, 116 b, and 116 c and the unexposedportions 116 d′ shown in FIG. 6B may be similar to the unexposedportions 116′, 116 a′, 116 b′, and 116 c′ described previously, andtherefore details of these structures are not repeated herein.

Generally, lithography processes, including an exposure process and adeveloping process, are commonly used in semiconductor manufacturingprocesses. However, when the lithography processes is performed on arelatively large area, the uniformity of the resulting pattern maybecome difficult to control. For example, there may be “on-focus”regions and “de-focus” regions when a resist layer is exposed in theexposure process, and the resolution at the “de-focus” regions may beworse than the “on-focus” regions. Accordingly, in some embodiments ofthe disclosure, the post treatment coating material (e.g. post treatmentcoating material 120, 120 a, 120 b, 120 c, and 120 d) and the posttreatment process are applied in the lithography processes, so thatresidues at the exposed portions (e.g. the remaining portions 306/406and/or the polymer layer 506) of the resist layer may be removed.Therefore, the resolution of the resulting pattern may be improved, andthe uniformity of the lithography process may also be improved.

Furthermore, the energy required for the lithography process may bereduced by performing the post treatment process described above. Morespecifically, the peripheral portion (e.g. the peripheral portion 124)of the unexposed portions may react with the post treatment coatingmaterial and may be removed by performing the second developing process.Therefore, the size of the unexposed portions (e.g. the unexposedportions 116′, 116 a′, 116 b′, 116 c′, and 116 d′) of the resist layerafter the second developing process is performed is smaller than thesize of the unexposed portions (e.g. the unexposed portions 116, 116 a,116 b, 116 c, and 116 d) of the resist layer before the seconddeveloping process is performed. Since the peripheral portion of theunexposed portions may not need to be exposed in the exposure process,the energy required for the lithography process may be reduced and thecost for performing the lithography process may also be reduced.

Embodiments of methods for performing a lithography process areprovided. The method may include performing an exposure process and adeveloping process on a resist layer to form an opening between theunexposed portions of the resist layer. Next, a post treatment coatingmaterial may be formed to cover the unexposed portions of the resistlayer and a post treatment process may be performed on the posttreatment coating material, so that a peripheral portion of theunexposed portions of the resist layer may be removed. Therefore, theenergy required for the lithography process may be reduced and theuniformity of the lithography process may be improved.

In some embodiments, a method for performing a lithography process isprovided. The method for performing a lithography process includesforming a resist layer over a substrate and exposing a portion of theresist layer to form an exposed portion between unexposed portions. Themethod for performing a lithography process further includes developingthe resist layer to remove the exposed portion of the resist layer suchthat an opening is formed between the unexposed portions and forming apost treatment coating material in the opening and over the unexposedportions of the resist layer. The method for performing a lithographyprocess further includes reacting a portion of the unexposed portions ofthe resist layer with the post treatment coating material by performinga post treatment process and removing the post treatment coatingmaterial.

In some embodiments, a method for performing a lithography process isprovided. The method for performing a lithography process includesforming a resist layer over a material layer and exposing an exposedportion of the resist layer by performing an exposure process. Themethod for performing a lithography process further includes dissolvinga first portion of the exposed portion of the resist layer in a firstdeveloper to form an opening in the resist layer, while a second portionof the exposed portion remains on the material layer. The method forperforming a lithography process further includes forming a posttreatment coating material in the opening and over the second portion ofthe exposed portion of the resist layer and reacting the post treatmentcoating material with the second portion of the exposed portion of theresist layer. The method for performing a lithography process furtherincludes removing the post treatment coating material and the secondportion of the exposed portion of the resist layer.

In some embodiments, a method for performing a lithography process isprovided. The method for performing a lithography process includesforming a resist layer over a substrate and exposing a portion of theresist layer to a radiation to form an exposed portion between unexposedportions of the resist layer. The method for performing a lithographyprocess further includes dissolving the exposed portion of the resistlayer in a first developer to form an opening between the unexposedportions of the resist layer and forming a post treatment coatingmaterial in the opening and over the unexposed portions of the resistlayer. The method for performing a lithography process further includesperforming a post treatment process on the post treatment coatingmaterial to release acids in the post treatment coating material andremoving the post treatment coating material and a peripheral portion ofthe unexposed portions.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method for performing a lithography process,comprising: forming a resist layer over a substrate; exposing a portionof the resist layer to form an exposed portion between unexposedportions; developing the resist layer to partially remove the exposedportion of the resist layer such that an opening is formed between theunexposed portions, wherein a first portion of a sidewall of theunexposed portion of the resist layer is covered by the exposed portionand a second portion of the sidewall of the unexposed portion of theresist layer is exposed through the opening; forming a post treatmentcoating material in the opening and over the unexposed portions of theresist layer; reacting a portion of the unexposed portions of the resistlayer with the post treatment coating material by performing a posttreatment process; and removing the post treatment coating material. 2.The method for performing a lithography process as claimed in claim 1,wherein the portion of the unexposed portions of the resist layerreacting with the post treatment coating material is removed with thepost treatment coating material.
 3. The method for performing alithography process as claimed in claim 2, wherein the portion of theunexposed portions of the resist layer removed during the seconddeveloping process has a thickness in a range from about 1 nm to about50 nm.
 4. The method for performing a lithography process as claimed inclaim 1, wherein the post treatment coating material comprises aphoto-acid generator, a thermal acid generator, or a combinationthereof.
 5. The method for performing a lithography process as claimedin claim 4, wherein the photo-acid generator has a molecular weight in arange from about 300 to about 1000, and the thermal acid generator has amolecular weight in a range from about 60 to about
 600. 6. The methodfor performing a lithography process as claimed in claim 1, wherein thepost treatment coating material comprises a polymer that comprises afirst functional group, and the first functional group is a moiety ofmethacrylic acid (MAA), methyl methacrylate (MMA), vinyl alcohol,hydroxystyrene (HS), 4-styrenesulfonic acid, fluoro-alcohol substitutedalkane, or a fluorine substituted alkane.
 7. The method for performing alithography process as claimed in claim 6, wherein the polymer furthercomprises a second functional group, and the second functional group isa moiety of a photo-acid generator or a thermal acid generator.
 8. Themethod for performing a lithography process as claimed in claim 1,wherein the post treatment process is a radiation curing process or athermal baking process.
 9. The method for performing a lithographyprocess as claimed in claim 8, wherein acids are released during thepost treatment process, and a pKa value of the acids is less than
 3. 10.A method for performing a lithography process, comprising: forming aresist layer over a material layer; exposing an exposed portion of theresist layer by performing an exposure process; dissolving a firstportion of the exposed portion of the resist layer in a first developerto form an opening in the resist layer, while a second portion of theexposed portion remains over the material layer; forming a posttreatment coating material in the opening and over the second portion ofthe exposed portion of the resist layer; reacting the post treatmentcoating material with the second portion of the exposed portion of theresist layer; and removing the post treatment coating material and thesecond portion of the exposed portion of the resist layer.
 11. Themethod for performing a lithography process as claimed in claim 10,wherein the post treatment coating material and the second portion ofthe exposed portion of the resist layer are removed by dissolving thepost treatment coating material and the second portion of the exposedportion of the resist layer in a second developer.
 12. The method forperforming a lithography process as claimed in claim 10, wherein thepost treatment coating material is heated to produce acids that reactwith the second portion of the exposed portion of the resist layer. 13.The method for performing a lithography process as claimed in claim 10,wherein a radiation curing process is performed on the post treatmentcoating material to produce acids that reacts with the second portion ofthe exposed portion of the resist layer.
 14. The method for performing alithography process as claimed in claim 10, wherein the second portionof the exposed portion of the resist layer is located at an upperportion of a sidewall of an unexposed portion of the resist layer. 15.The method for performing a lithography process as claimed in claim 10,wherein the post treatment coating material comprises a photo-acidgenerator or a thermal acid generator.
 16. The method for performing alithography process as claimed in claim 10, wherein a width of theopening in the resist layer is enlarged by removing the second portionof the exposed portion of the resist layer.
 17. A method for performinga lithography process, comprising: forming a resist layer over asubstrate; exposing a portion of the resist layer to a radiation to forman exposed portion between unexposed portions of the resist layer;dissolving the exposed portion of the resist layer in a first developerto form an opening between the unexposed portions of the resist layerand to form a polymer layer between the unexposed portions of the resistlayer; forming a post treatment coating material in the opening, overthe polymer layer, and over the unexposed portions of the resist layer;performing a post treatment process on the post treatment coatingmaterial to release acids in the post treatment coating material; andremoving the post treatment coating material and a peripheral portion ofthe unexposed portions.
 18. The method for performing a lithographyprocess as claimed in claim 17, wherein the acids in the post treatmentprocess react with the peripheral portion of the unexposed portions. 19.The method for performing a lithography process as claimed in claim 17,wherein the post treatment coating material and the peripheral portionof the unexposed portions are removed by dissolving the post treatmentcoating material and the peripheral portion of the unexposed portions ina developer.
 20. The method for performing a lithography process asclaimed in claim 17, further comprising: removing the polymer layer withthe post treatment coating material and the peripheral portion of theunexposed portions.